Call by reference depreciated

I'm using PHP5 and seeing errors on lines 616 and 659 about call by reference being depreciated

616c616
<         $errors = array_merge((array)$errors, (array)$function(&$node, $preview > 0));
---
>         $errors = array_merge((array)$errors, (array)$function($node, $preview > 0));
659c659
<         $output .= $function(&$node, $preview > 0, count($errors) > 0); 
---
>         $output .= $function($node, $preview > 0, count($errors) > 0);